The advantages of wideband data transmission over single-mode optical fibers is becoming more apparent in view of the recent development of more pure silicas which make up the cores and claddings. Freely available silica can be processed to have relatively low attenuations particularly at 1.55 .mu.m. Recent processes have allowed the fabrication of low-loss 0.2 db-per-kilometer fibers.
The analysis of Dr. Ching T. Chang in his paper entitled "Minimum Dispersion in a Single-Mode Step-Index Optical Fiber" appearing in Applied Optics, 1979, 18, pages 2516-2522 concerned itself with the cancellation between the material and waveguide dispersions to predict a shift in the minimum dispersion wavelengths .lambda..sub.o for achieving total minimum dispersion in single-mode step-index fibers. The paper dealt extensively with various single-mode step-index fibers and predicted minimum dispersion wavelengths to achieve zero first order dispersion accurately. By solving the LP.sub.01 mode characteristic equation, Dr. Chang could calculate accurately how much of the LP.sub.01 mode of waveguide dispersion was needed for cancellation of the material dispersion. This greater accuracy in waveguide dispersion was found to result in a significant change in the minimum dispersion wavelength and second order residual dispersion; however, a further analysis set forth in the above referenced pending patent application provided fabricators the necessary information for making minimum loss and minimum dispersion single-mode step-index fibers at the single 1.55 .mu.m wavelength.
From all indications, single-mode fibers are being more widely used where increasing amounts of data must be handled. Although the data carrying capabilities of such fibers is considerable, with increasing data carrying demands, the data carrying capabilities of the fibers should be increased themselves.
Thus there is a continuing need of the state-of-the-art to develop multichannel single-mode fibers having the capability of transmitting vast amounts of data over a long distance.